Ultima,
1. Do you agree that our brains follow the laws of physics?
If the laws of physics include those of biology, yes, in the sense that the way our brain functions is biological in nature. The brains of apes follow the same laws of physics that human brains do, but they both don’t operate the same. Neither do two human brains operate the same. In fact, to be more specific, I don’t think there are clear biological laws that can generalize the human brain. The human brain is an aggregate of chemicals, other physical masses, and then biological methods of interactions with one another. These develop in different ways depending on the experiences the brain, or whatever part of the brain is responsible for reception and interpretation, throughout the life of a human being.
2. Do you believe that there is something magical or mysterious about them?
In what sense of those two words?
3. If you don’t, then you must accept that the human brain, and everything that it can do, will one day be computable and artificially mimicked, even if by brute force alone.
This is a non-sequitur; it doesn’t follow from the previous two (arguable) premises. Human beings can’t even map out the method by which they themselves arrive at ideas. How can they give this function to a robot?
You are probably right over the very long run, but there are going to be a lot of unhappy forklift drivers and the like in the meantime. The effects could be much more profound than even the industrial revolution. The whole nature of rapid technological change is that it is very hard to predict the outcomes, but we can see that they will be rapid, and large.
Be this as it may, in an economy with rapid technological improvement, the structure of it changes just as rapidly. Meaning, just as some jobs are eliminated, others are created. The idea of long-term structural unemployment is simply untenable. There may be a decrease in the amount of hours an individual may believe are necessary to work, but as others have pointed out this is a natural byproduct of capitalism.